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Author Topic: Gasoline & Kerosine Mix?  (Read 21133 times)

Jim Mc

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Re: Gasoline & Kerosine Mix?
« Reply #15 on: July 03, 2008, 02:58:30 AM »
A fuel's octane rating is it's ability to resist pre-ignition - often called "knock." The higher the octane number, the less propensity there is for a fuel to pre-ignite under a given set of conditions. This standard is for gasoline. It isn't necessarily true that a fuel with a higher octane number will do anything for your engine, unless it's designed to make use of it. Like if it's turbo- or super-charged, or it has a high compression ratio.

No argument from me with your statements above – all pretty basic stuff so far.

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Diesel fuel has a theoretical octane number somewhere north of 3000,

Wow, I had no idea.  Sure would like to learn more about this fact.  Got any reference you could point me to?


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A molecule's "carbon chain length" is only indirectly related to a fuel's octane number.

Agreed, but do longer chains increase knocking tendency or not? 

According to Internal Combustion Engines, McGraw Hill, 1939, they do.  And they show that in the case of, say, straight chain saturated hydrocarbons, knocking tendency is pretty linearly related to chain length.  Same holds for other structures.  Granted, an old text, but it’d be surprising if this volume, in it’s 5th edition has this relationship backwards…

That said, their presentation is a little fuzzy, as they don’t exactly define what is meant by “knocking tendency”. 


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I would suspect that what you are hearing is not actually "knock" (pre-ignition), but something else. Possibly detonation. Possibly your engine's death rattle, as it burns a fuel at temperatures and pressures far in excess of those it was designed for... but hey, I'm not there, maybe it's something else.

It was knocking, as I stated.  I know the sound, and it occurred under heavy load.  With pure gasoline, the engine does not make this sound. My experience with this knocking was based on a air cooled single cylinder lawnmower engine.

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Adding middle distillates (diesel, kerosene, jet, furnace) to gasoline for use in a gasoline engine would actually increase the octane rating (resistance to pre-ignition) of the fuel....

I still disagree with this, but look forward to your evidence backing it up...


« Last Edit: July 03, 2008, 03:11:14 AM by Jim Mc »

tiger

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Re: Gasoline & Kerosine Mix?
« Reply #16 on: July 04, 2008, 03:00:33 AM »
Cognos:
I enjoy your comments! Could you talk about Cetane a bit? maybe a new thread, but an introduction here for me would be nice!
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Jim Mc

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Re: Gasoline & Kerosine Mix?
« Reply #17 on: July 04, 2008, 05:25:06 AM »
You’ve made two claims:

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Diesel fuel has a theoretical octane number somewhere north of 3000,

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Adding middle distillates (diesel, kerosene, jet, furnace) to gasoline for use in a gasoline engine would actually increase the octane rating (resistance to pre-ignition) of the fuel....

stated them with authority, and now refuse to debate them, stand behind them, or admit they were wrong.  Rather, it seems you expect me to believe you because of your stature in the field.  It’s my nature to challenge authorities, and I’m generally the first person in a room to announce it when the emperor has no clothes.  I don’t agree with these claims, and concisely stated my reasoning.

Also, why apologize for being too technical?  This is a forum of people interested  in technical details.  It’s not necessary to skip the details when backing up a position.  But, if you’re gonna get ‘technical’, it better be right.  No need to create a smokescreen with verbiage, either.

oliver90owner

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Re: Gasoline & Kerosine Mix?
« Reply #18 on: July 04, 2008, 07:41:49 AM »
Didn't petrol come in different octane ratings?  I recall 'commercial' was around 70?  They didnt sell it as 'RON#' in those days but top grades were 'super' or whatever.  That probably meant the octane rating could have been as low as 60 and as high as 100 or even wider range.

And that was just simple petrol with tetra ethyl lead as antiknock additive?  Presumably less additive equated to lower rating for otherwise same fuel stock? 

On same basis, add kero (no additives) and down goes additive content, down goes anti knock rating?  Does this seem too simple? I agree it is, but that is the way with fuels and octane rating - a little of something can or might make a big difference to the rating.

Regards, RAB

JimB

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Re: Gasoline & Kerosine Mix?
« Reply #19 on: July 04, 2008, 01:46:59 PM »
I work on and run a lot of diesel and gas engines including 3 WVO engines. My simplified take on all this is that diesel fuels are rated by cetane and gas is rated by octane. The scales work in almost opposite directions. Cetane measures a fuels ability to ignite under compression while octane measures a fuels ability not to ignite under compression(pre-ignition). By introducing the heavier distillates to gasoline it will make the engine ping easier which might be ok if it's a low compression low performance engine. By adding gasoline to diesels(which many do to blend WVO or for a winter starting aid), the fuel tends to combust quciker during starting. This is just my experience.YMMV. ;D
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mkdutchman

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Re: Gasoline & Kerosine Mix?
« Reply #20 on: July 04, 2008, 08:31:17 PM »
cognos,
That is an excellent post. Just the right amount of information combined with a dash of sarcasm, served with a liberal portion of explaining. Perfect  :D ;D ;D
« Last Edit: July 04, 2008, 08:33:03 PM by mkdutchman »

BACKROAD

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Re: Gasoline & Kerosine Mix?
« Reply #21 on: August 16, 2008, 10:10:43 PM »
I'm so sorry guys.  I didn't think that this question would come to near fisticuffs.  My conclusion to my original question is that mixing Kerosine with Gasoline in a gas engine (this case is a generator) is not a good thing.  I'm saving all of my "purchased cheaply" Tiki Torch Oil (aka Kerosine) for my 195 Dungfong Diesels.  At least in the Diesel, I know I'm in the safe zone.  :):):)


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tiger

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Re: Gasoline & Kerosine Mix?
« Reply #22 on: August 17, 2008, 03:06:36 AM »
Cognos:
Wikipedia is like pouring athletes foot medicine on your shoes! Cetane Please!
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